Plant and Method for Treating Loamy Debris

ABSTRACT

The invention relates to a treatment plant for loamy surplus soil from a construction site. It is characterised in that said plant comprises: a vibrating hopper, known as inlet hopper; a conveyor, known as weighing, integrating continuous weighing means of the transported load; at least one storage tank for a binder; dosing means of the binder as a function of the weighing carried out at the level of the weighing conveyor; mixing means of a loam/binder ensemble for producing a material suitable as backfill which can be compacted as it leaves the plant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a 371 national phase application of PCT/FR2006/001800 filed 24 Jul. 2006, claiming priority to French Patent Application No. FR 0508162 filed 29 Jul. 2005, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a treatment plant for loamy surplus soil from a construction site.

The invention also relates to a method for treating this loamy surplus soil and resulting materials.

The invention will find its principal application in making materials usable as fill materials from loamy surplus soil.

However, this application is not limiting and the resulting materials could find other uses such as in embankments.

BACKGROUND OF THE INVENTION

In the field of public works, earthworks are often carried out either for building construction foundations or even for passage of pipelines or cables.

The resulting surplus soil must either be utilised after treatment, or stockpiled, especially in burial sites.

It is certain that transporting this surplus soil requires a large number of lorry trips, leading to significant environmental and economic costs. It is thus particularly interesting for building and public works enterprises to use this surplus soil directly at the construction site.

Furthermore, once the earthworks are completed, it may be necessary to backfill the trenches. To do this, fill materials are provided, these materials having to have precise characteristics to respect current standards and especially with respect to their physical, mechanical and chemical properties of these materials.

Because the surplus soil removed from the construction site is not homogeneous, it cannot be used as fill material.

In particular, the loam removed from the construction site comprises excessive water content and must be dried prior to being used as fill material.

Different methods have been proposed for treating loams by adding one or more additives, one of the additives having a drying reaction on the loam.

However, with existing methods there is the problem of dosage of the additive relative to the quantity of loam treated.

It is important to note that at this level, precise dosage must be made so as to obtain at output a fill material having physical, chemical and mechanical characteristics known in advance.

The solutions proposed to date are not satisfactory on this point since they propose dosage:

-   -   which is either manual dosage of the quantity of additive which         is very imprecise, especially because it is not adjusted in real         time,     -   or automatic adjusting as a function of a volume of material to         be treated which is also imprecise, since the density of the         material to be treated is not known for certain,     -   or again automatic adjusting as a function of the travel speed         of a conveyor carrying the materials to be treated which is         again a highly imprecise method considering the irregularity of         the feed of the conveyor.

SUMMARY OF THE INVENTION

The aim of the present invention is to remedy the above disadvantages and for this purpose, to propose a treatment plant for loamy surplus soil from a construction site to produce at output materials suitable for backfilling, and whereof the physical, mechanical and chemical characteristics are adjusted by the plant.

Another object of the present invention is to build a treatment plant for loamy surplus soil from a construction site in which the surplus soil can be mixed with one or more additives so as to modify the physical, mechanical and chemical characteristics of the material at output.

Another object of the present invention is to propose a treatment plant for loamy surplus soil from a construction site comprising mixing means to produce at output materials with a granulometry or controlled granulometric spindle.

Another object of the present invention is to propose a treatment plant for loamy surplus soil from a construction site comprising means for analysing the characteristics of the materials obtained at output.

Another object of the present invention is to propose a treatment plant for loamy surplus soil from a construction site in which the various basic elements form a compact ensemble so as to be mobile on the construction site.

For this purpose, the present invention proposes a treatment plant for loamy surplus soil from a construction site such that, according to the invention, the plant comprises:

-   -   a vibrating hopper, known as inlet hopper;     -   a conveyor, known as weighing, integrating continuous weighing         means of the transported load;     -   at least one storage tank for a binder;     -   dosing means of the binder as a function of the weighing carried         out at the level of the weighing conveyor;     -   mixing means of a loam/binder assembly for producing material         suitable as backfill which can be compacted as it leaves the         plant.

Another aim of the invention is a method for treating loamy surplus soil from a construction site used in the treatment plant for loamy surplus such as mentioned hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge more clearly from the following description of a preferred embodiment, in which the description is given only by way of non-limiting example in reference attached diagrams, in which:

FIG. 1 schematically illustrates in side elevation an embodiment of the device according to the invention, certain parts of the plant being made transparent for easier comprehension of the plant;

FIG. 2 illustrates the plant in FIG. 1 coupled to an inlet conveyor and to a an outlet conveyor;

FIG. 3 illustrates a plan view of the assembly illustrated in FIG. 2.

DETAILED DESCRIPTION

FIG. 1 mainly illustrates a treatment plant 1 for loamy surplus soil.

This plant comprises:

-   -   a vibrating hopper 2, known as inlet hopper;     -   a conveyor 3, known as weighing, integrating continuous weighing         means 4 of the transported load;     -   at least one storage tank 5 for a binder;     -   dosing means 6 of the binder as a function of the weighing         carried out at the level of the conveyor 3.

The plant also comprises mixing means 7 of the loam/binder mixture for producing material suitable as backfill which can be compacted as it leaves the plant 1.

Said vibrating hopper 2 will advantageously be equipped in its lower part with a screen 12 for evacuating the upper fraction allowed by the mixer.

Advantageously, the inlet hopper 2 will be an anti-silting type.

Said vibrating hopper 2 could also be connected to a coarse sieve, so as to facilitate passage of the chunky loam and its reception on the weighing conveyor 3.

Advantageously, the different elements will be secured to a structure 8 for ensuring the compactness of the plant and making the plant mobile.

Accordingly, the treatment plant 1 can be transported by an Ampliroll truck or float, then placed on the ground in a fixed position or be shifted on the construction site.

Prehension elements for manipulation of the plant, especially by means of slings, could especially be provided at the level of the structure 8.

As shown earlier, the treatment plant for surplus soil comprises at least one storage tank for a binder 5.

This binder will advantageously be lime for evaporating water and reducing the water content of the loam.

Other additives could, however, also be added as a function of the specific qualities expected for the final product.

The quantity of binder is delivered to the mixing means 7 from dosing means 6.

These dosing means 6 advantageously allow dosage by weighing the binders as a function of the weighing carried out at the level of the second conveyor 3.

In this way, it is possible from the present invention to produce highly precise dosage per quantity of material contributed from the binders to produce at output a final product whereof the water content is homogeneous and whereof the proportion of binder is also identical.

To ensure mixing of the loam/binder mix, the mixing 7 will advantageously be done using a dual-axle multi-arm and palette mixer.

Of course, other means known to the expert could have been envisages for completing mixing.

The weighing means 4 of the transported load by the conveyor 3 are preferably constituted by a set of sensors 4 positioned at the level of the conveyor 3. These could especially be Peson-type sensors.

To make it easier to use the plant 1, an additional conveyor known as a feed conveyor 9 could also be provided, as in FIG. 3.

In the same way, an outlet conveyor 10 for transporting the product final obtained could be provided at output of the mixing means 7.

According to another advantageous characteristic of the invention, additional delivery means, not shown in the attached diagrams, for a binder could also be provided at the level of the vibrating hopper 2.

This characteristic will be particularly useful whenever the loams have a high water content.

According to another advantageous characteristic of the invention mixing means of the mixture 7 and measuring means of the humidity rate of the final product obtained could also be provided at output.

These could especially be for measuring the humidity rate for microwave techniques.

In this respect, the dosing means 6 comprise treatment means 11 of the product emanating from the weighing means 4 so as to adapt the quantity of binder to be delivered, these treatment means 11 also comprising manual and automatic regulation means by which the given material relative to the product to be obtained are introduced at output.

In the variant in which measuring means of the humidity rate of the product final are used, it could also be provided that these treatment means 11 are connected to the measuring means of the water content so as to constitute a regulation loop between the given material entered manually or automatically, the given material coming from the weighing means and the given material coming from the measuring means of the water content.

The aim of the invention is also a method for utilising the above plant.

In this method, the following steps are taken successively:

-   -   conveying surplus soil to the vibrating hopper 2;     -   filling surplus soil into said vibrating hopper 2;     -   conveying and weighing surplus soil by means of the conveyor 3         and measuring means of the weighing 4;     -   dosage of at least one binder as a function of the weighing;     -   mixing of the surplus soil/binder mix by means of mixing means         7;     -   recovery of the backfill material obtained at output.

It is important to note that dosage made in the dosing means 6 depends on the weighing carried out by the measuring means 4, but also of the given material entered manually at the level of the treatment means 11. By way of example, the operator can enter information relative to the final product to be obtained at the level of the treatment means 11, and especially its humidity rate and also the expected humidity rate of the surplus soil, this rate being obtained from previous analysis of the loam.

It is also important to note that, if the humidity rate of the surplus soil is considerable, a previous drying step of the loam at the level of the inlet vibrating hopper 2 will be undertaken.

According to an advantageous characteristic of the invention, an additional step for verification of the water content of the final product could also be provided, especially from a microwave technique at the level of the treatment method.

It is understood that other embodiments familiar to the expert could also have been envisaged without departing from the scope of the patent defined by the following claims. 

1. A treatment plant for loamy surplus soil from a construction site, said plant comprising: a vibrating hopper, known as inlet hopper; a conveyor, known as weighing, integrating continuous weighing devices of the transported load; at least one storage tank for a binder; a dosing device of the binder as a function of the weighing carried out at the level of the weighing conveyor; a mixing device of a loam/binder mix to produce a material suitable as backfill which can be compacted as it leaves the plant.
 2. The treatment plant as claimed in claim 1, comprising a delivery device of a binder at the level of the vibrating hopper.
 3. The treatment plant as claimed in claim 1, comprising a conveyor known as a feed conveyor for introducing loam to the vibrating hopper.
 4. The treatment plant as claimed in claim 1, in which the vibrating hopper comprises a screen at the bottom of the hopper and is coupled to a coarse sieve.
 5. The treatment plant as claimed in claim 1, comprising two storage tanks with an independent dosing device.
 6. The treatment plant as claimed in claim 1, in which the weighing devices are constituted by a set of sensors spaced apart at the level of the conveyor and allowing continuous weighing of the transported load.
 7. The treatment plant as claimed in claim 1, in which mixing device, measuring means of the humidity rate of the material suitable as backfill which can be compacted are provided at output.
 8. The treatment plant as claimed in claim 1, in which the vibrating hopper, the weighing conveyor, said at least one storage tank, the dosing device of the binder and the mixing device are secured to an armature such that they can shift the treatment plant.
 9. A method for treatment of loamy surplus soil using a treatment plant as claimed in claim 1, in which the following steps are successively carried out: a step for conveying surplus soil to a vibrating hopper a step for filling surplus soil in the hopper; a step for conveying and weighing surplus soil by means of a conveyor and weighing devices; a dosage step of at least one binder as a function of the weighing carried out by the dosing device; a mixing step of the surplus soil/binder mix; a recovery step of the material suitable as backfill obtained at output.
 10. The treatment method as claimed in claim 9, in which a verification step of the water content of the material suitable as backfill is also provided at output. 